The present invention relates generally to a device for cutting both hard and soft materials and, more particularly, to a device for combining electromagnetic and hydro energies for cutting and removing both hard and soft tissues.
Turning to FIG. 1, a prior art optical cutter for dental use is disclosed. According to this prior art apparatus, a fiber guide tube 5, a water line 7, an air line 9, and an air knife line 11 (which supplies pressurized air) are fed into the hand-held apparatus 13. A cap 15 fits onto the hand-held apparatus 13 and is secured via threads 17. The fiber guide tube 5 abuts within a cylindrical metal piece 19. Another cylindrical metal piece 21 is a part of the cap 15.
When the cap 15 is threaded onto the hand-held device 13, the two cylindrical metal tubes 19 and 21 are moved into very close proximity of one another. A gap of air, however, remains between these two cylindrical metal tubes 19 and 21. Thus, the laser within the fiber guide tube 5 must jump this air gap before it can travel and exit through another fiber guide tube 23. Heat is dissipated as the laser jumps this air gap.
The pressurized air from the air knife line 11 surrounds and cools the laser as the laser bridges the gap between the two metal cylindrical objects 19 and 21. Thus, a first problem in this prior art apparatus is that the interface between the two metal cylindrical objects 19 and 21 has a dissipation of heat which must be cooled by pressurized air from the air knife line 11. (Air from the air knife line 11 flows out of the two exhausts 25 and 27 after cooling the interface between elements 19 and 21.) This inefficient interface between elements 19 and 21 results from the removability of the cap 15, since a perfect interface between elements 19 and 21 is not achieved.
The laser energy exits from the fiber guide tube 23 and is applied to a target surface within the patient""s mouth, according to a predetermined surgical plan. Water from the water line 7 and pressurized air from the air line 9 are forced into the mixing chamber 29. The air and water mixture is very turbulent in the mixing chamber 29, and exits this chamber through a mesh screen with small holes 31. The air and water mixture travels along the outside of the fiber guide tube 23, and then leaves the tube and contacts the area of surgery. This air and water spray coming from the tip of the fiber guide tube 23 helps to cool the target surface being cut and to remove cut materials by the laser. The need for cooling the patient surgical area being cut is another problem with the prior art.
In addition to prior art systems which utilize laser light from a fiber guide tube 23, for example, to cut tissue and use water to cool this cut tissue, other prior art systems have been proposed. U.S. Pat. No. 5,199,870 to Steiner et al., which issued on Apr. 6, 1993, discloses an optical cutting system which utilizes the expansion of water to destroy and remove tooth material. This prior art approach requires a film of liquid having a thickness of between 10 and 200 mm. Another prior art system is disclosed in U.S. Pat. No. 5,267,856 to Wolbarsht et al., which issued on Dec. 7, 1993. This cutting apparatus is similar to the Steiner et al. patent, since it relies on the absorption of laser radiation into water to thereby achieve cutting.
Similarly to the Steiner et al. patent, the Wolbarsht et al. patent requires water to be deposited onto the tooth before laser light is irradiated thereon. Specifically, the Wolbarsht et al. patent requires water to be inserted into pores of the material to be cut. Since many materials, such as tooth enamel, are not very porous, and since a high level of difficulty is associated with inserting water into the xe2x80x9cporesxe2x80x9d of many materials, this cutting method is somewhat less than optimal. Even the Steiner et al. patent has met with limited success, since the precision and accuracy of the cut is highly dependent upon the precision and accuracy of the water film on the material to be cut. In many cases, a controllable water film cannot be consistently maintained on the surface to be cut. For example, when the targeted tissue to be cut resides on the upper pallet, a controllable water film cannot be maintained.
The above-mentioned prior art systems have all sought in vain to obtain xe2x80x9ccleannessxe2x80x9d of cutting. In several dental applications, for example, a need to excise small amounts of soft tissues and/or hard tissues with a great degree of precision has existed. These soft tissues may include gingiva, frenum, and lesions and, additionally, the hard tissues may include dentin, enamel, bone, and cartilage. The term xe2x80x9ccleannessxe2x80x9d of cutting refers to extremely fine, smooth incisions which provide ideal bonding surfaces for various biomaterials. Such biomaterials include cements, glass ionomers and other composites used in dentistry or other sciences to fill holes in structures such as teeth or bone where tooth decay or some other defect has been removed. Even when an extremely fine incision has been achieved, the incision is often covered with a rough surface instead of the desired smooth surface required for ideal bonding.
One specific dental application, for example, which requires smooth and accurate cutting through both hard and soft tissues is implantology. According to the dental specialty of implantology, a dental implant can be installed in a person""s mouth when that person has lost his or her teeth. The conventional implant installation technique is to cut through the soft tissue above the bone where the tooth is missing, and then to drill a hole into the bone. The hole in the bone is then threaded with a low-speed motorized tap, and a titanium implant is then screwed into the person""s jaw. A synthetic tooth, for example, can be easily attached to the portion of the implant residing above the gum surface. One problem associated with the conventional technique occurs when the clinician drills into the patient""s jaw to prepare the site for the implant. This drilling procedure generates a great deal of heat, corresponding to friction from the drilling instrument. If the bone is heated too much, it will die. Additionally, since the drilling instrument is not very precise, severe trauma to the jaw occurs after the drilling operation. The drilling operation creates large mechanical internal stress on the bone structure.
The present invention discloses an electromagnetically induced cutting mechanism, which can provide accurate cutting operations on hard and soft tissues, and other materials, as well. The electromagnetically induced cutter is capable of providing extremely fine and smooth incisions, irrespective of the cutting surface. Additionally, a user programmable combination of atomized particles allows for user control of various cutting parameters. The various cutting parameters may also be controlled by changing spray nozzles and electromagnetic energy source parameters. Applications for the present invention include medical, dental, industrial (etching, engraving, cutting and cleaning) and any other environments where an objective is to precisely remove surface materials without inducing thermal damage, uncontrolled cutting parameters, and/or rough surfaces inappropriate for ideal bonding. The present invention further does not require any films of water or any particularly porous surfaces to obtain very accurate and controllable cutting.
Drills, saws and osteotomes are standard mechanical instruments used in a variety of dental and medical applications. The limitations associated with these instruments include: temperature induced necrosis (bone death), aerosolized solid-particle release, limited access, lack of precision in cutting depth and large mechanical stress created on the tissue structure. The electromagnetically induced mechanical cutter of the present invention is uniquely suited for these dental and medical applications, such as, for example, implantology. In an implantology procedure the electromagnetically induced mechanical cutter is capable of accurately and efficiently cutting through both oral soft tissues overlaying the bone and also through portions of the jawbone itself. The electromagnetically induced mechanical cutter of the present invention does not induce thermal damage and does not create high internal structural stress on the patient""s jaw, for example. After the patient""s jaw is prepared with the electromagnetically induced mechanical cutter, traditional methods can be employed for threading the hole in the patient""s jaw and inserting the dental implant. Similar techniques can be used for preparing hard tissue structures for insertion of other types of medical implants, such as pins, screws, wires, etc.
The electromagnetically induced mechanical cutter of the present invention includes an electromagnetic energy source, which focuses electromagnetic energy into a volume of air adjacent to a target surface. The target surface may be a tooth, for example. A user input device specifies whether either a high resolution or a low resolution cut is needed, and further specifies whether a deep penetration cut or a shallow penetration cut is needed. An atomizer generates a combination of atomized fluid particles, according to information from the user input device. The atomizer places the combination of atomized fluid particles into the volume of air adjacent to the target surface. The electromagnetic energy, which is focused into the volume of air adjacent to the target surface, is selected to have a wavelength suitable for the fluid particles. In particular, the wavelength of the electromagnetic energy should be substantially absorbed by the atomized fluid particles in the volume of air adjacent to the target surface to thereby explode the atomized fluid particles. Explosion of the atomized fluid particles imparts mechanical cutting forces onto the target surface.
The user input device may incorporate only a single dial for controlling the cutting efficiency, or may include a number of dials for controlling the fluid particle size, fluid particle velocity, spray cone angle, average laser power, laser repetition rate, fiberoptic diameter, etc. According to one feature of the present invention, the atomizer generates relatively small fluid particles when the user input specifies a high resolution cut, and generates relatively large fluid particles when the user input specifies a low resolution cut. The atomizer generates a relatively low density distribution of fluid particles when the user input specifies a deep penetration cut, and generates a relatively high density distribution of fluid particles when the user input specifies a shallow penetration cut. A relatively small fluid particle may have a diameter less than the wavelength of the electromagnetic energy and, similarly, a relatively large fluid particle may have a diameter which is greater than the wavelength of the electromagnetic energy.
The electromagnetic energy source preferably is an erbium, chromium, yttrium, scandium, gallium garnet (Er, Cr:YSGG) solid state laser, which generates electromagnetic energy having a wavelength in a range of 2.70 to 2.80 microns. According to other embodiments of the present invention, the electromagnetic energy source may be an erbium, yttrium, scandium, gallium garnet (Er:YSGG) solid state laser, which generates electromagnetic energy having a wavelength in a range of 2.70 to 2.80 microns; an erbium, yttrium, aluminum garnet (Er:YAG) solid state laser, which generates electromagnetic energy having a wavelength of 2.94 microns; chromium, thulium, erbium, yttrium, aluminum garnet (CTE:YAG) solid state laser, which generates electromagnetic energy having a wavelength of 2.69 microns; erbium, yttrium orthoaluminate (Er:YAL03) solid state laser, which generates electromagnetic energy having a wavelength in a range of 2.71 to 2.86 microns; holmium, yttrium, aluminum garnet (Ho:YAG) solid state laser, which generates electromagnetic energy having a wavelength of 2.10 microns; quadrupled neodymium, yttrium, aluminum garnet (quadrupled Nd:YAG) solid state laser, which generates electromagnetic energy having a wavelength of 266 nanometers; argon fluoride (ArF) excimer laser, which generates electromagnetic energy having a wavelength of 193 nanometers; xenon chloride (XeCl) excimer laser, which generates electromagnetic energy having a wavelength of 308 nanometers; krypton fluoride (KrF) excimer laser, which generates electromagnetic energy having a wavelength of 248nanometers; and carbon dioxide (CO2), which generates electromagnetic energy having a wavelength in a range of 9.0 to 10.6 microns.
When the electromagnetic energy source is configured according to the preferred embodiment, the repetition rate is greater than 1 Hz, the pulse duration range is between 1 picosecond and 1000 microseconds, and the energy is greater than 1 millijoule per pulse. According to one preferred operating mode of the present invention, the electromagnetic energy source has a wavelength of approximately 2.78 microns, a repetition rate of 20 Hz, a pulse duration of 140 microseconds, and an energy between 1 and 300 millijoules per pulse. The atomized fluid particles provide the mechanical cutting forces when they absorb the electromagnetic energy within the interaction zone. These atomized fluid particles, however, provide a second function of cleaning and cooling the fiberoptic guide from which the electromagnetic energy is output.
The optical cutter of the present invention combats the problem of poor coupling between the two laser fiberoptics of FIG. 1. The optical cutter of the present invention provides a focusing optic for efficiently directing the energy from the first fiberoptic guide to the second fiberoptic guide, to thereby reduce dissipation of laser energy between the first fiberoptic guide and the second fiberoptic guide. This optical cutter includes a housing having a lower portion, an upper portion, and an interfacing portion. The first fiberoptic tube is surrounded at its upper portion by a first abutting member, and the second fiberoptic tube is surrounded at its proximal end by a second abutting member. A cap is placed over the second fiberoptic tube and the second abutting member. Either fiberoptic tube may be formed of calcium fluoride (CaF), calcium oxide (CaO2), zirconium oxide (ZrO2), zirconium fluoride (ZrF), sapphire, hollow waveguide, liquid core, TeX glass, quartz silica, germanium sulfide, arsenic sulfide, and germanium oxide (GeO2).
The electromagnetically induced mechanical cutter of the present invention efficiently and accurately cuts both hard and soft tissue. This hard tissue may include tooth enamel, tooth dentin, tooth cementum, bone, and cartilage, and the soft tissues may include skin, mucosa, gingiva, muscle, heart, liver, kidney, brain, eye, and vessels.